I'm at work right now, and I just realized that I missed my pill this morning...

Is it safe to have sex today?... if I take it right when I go home? I'll be home at 5... And probably have sex later that night...

Read your package insert.

While it's probably "safe" different pills have different protocols when a pill is missed. Usually, as long as the pill isn't missed completely (a whole day late), there's no problem. However, some pills are effected by even a few hours, and it can depend on what week of your cycle you're on.